CA PLS Exam Preparation

Comprehensive preparation for the California Professional Land Surveyor (PLS) exam. Based on the January 2025 Test Plan with 6 modules and 57 topics. Content adapted from CalTrans LS/LSIT Video Exam Preparation Course materials.

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Lesson 7

Hydrographic Surveys

Hydrographic Surveys

Overview

Hydrographic surveys determine underwater topography, water depths, and shoreline positions. These surveys support navigation, dredging, flood control, and property boundary determination.

Learning Objectives

  • Understand hydrographic survey methods
  • Collect bathymetric data
  • Determine shoreline boundaries
  • Produce hydrographic products

Key Concepts

Depth Measurement Methods

Techniques for measuring water depth:

  • Single-beam sonar
  • Multi-beam sonar
  • Lead line (traditional)
  • Sub-bottom profiling
  • LiDAR (shallow water)

Positioning for Hydrography

Locating depth measurements:

  • GNSS positioning
  • Range-azimuth methods
  • Acoustic positioning
  • Integrated systems

Tidal Considerations

Accounting for water levels:

  • Tidal datum references
  • Water level observations
  • Gauge installation
  • Datum conversions

Boundary Applications

Hydrographic surveys for boundaries:

  • Mean high/low water determination
  • Ordinary high water mark
  • Navigable water boundaries
  • Riparian and littoral rights

Key Terms

  • Bathymetry: Measurement of water depths
  • Sounding: Individual depth measurement
  • Tidal Datum: Reference surface for water levels

Practice Questions

  1. What methods are used to measure water depths in hydrographic surveys?
  2. How are soundings referenced to a consistent vertical datum?